Apple recently released iOS 4.2 for all devices— iPad, iPhone and iPod Touch— and one of the best features is AirPlay, which lets you stream video directly to AppleTVs. There's only one problem— it will only stream video that meet's Apple's specifications.

This video from lifehacker shows you how to resolve this video problem in AirPlay by encoding those movies with either MPEG4 or H.264 codecs. Actually, it's best to just stick with H.246. In order to start making your videos AppleTV compatible, you'll need HandBrake, which is a totally free software that will save your life in more ways than one.

Download HandBrake here for Mac, Windows, Ubuntu, Fedora and more. You can also use a similar video encoder, as long as you can create an H.264 .MP4 file. Here are the settings to use: